Autoimmunity
STAT1 signaling protects self-reactive T cells from control by innate cells during neuroinflammation
Abstract
The transcription factor Signal transducer and activator of transcription 1 (STAT1) plays a critical role in modulating the differentiation of CD4+ T cells producing IL-17 and GM-CSF, which promote the development of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). The protective role of STAT1 in MS and EAE has been largely attributed to its ability to limit pathogenic T helper (Th) cells and promote regulatory T (Treg) cells. Using mice with selective deletion of STAT1 in T cells (STAT1CD4-Cre), we identify a novel mechanism by which STAT1 regulates neuroinflammation independently of Foxp3+ Treg cells. STAT1-deficient effector T cells become the target of NK cell-mediated killing, limiting their capacity to induce EAE. STAT1-deficient T cells promoted their own killing by producing more IL-2 that in return activated NK cells. Elimination of NK cells restored EAE susceptibility in STAT1CD4-Cre mice. Therefore, our study suggests that the STAT1 pathway can be manipulated to limit autoreactive T cells during autoimmunity directed against the central nervous system.
Authors
Carlos A. Arbelaez, Pushpalatha Palle, Jonathan Charaix, Estelle Bettelli
Abstract
Biological aging is the strongest factor associated with the clinical phenotype of multiple sclerosis (MS). Relapsing remitting MS (RRMS) typically presents in the third or fourth decade, while the mean age of presentation of progressive MS (pMS) is 45 years old. Here we show that experimental autoimmune encephalomyelitis (EAE), induced by the adoptive transfer of encephalitogenic CD4+ Th17 cells, is more severe, and less like to remit, in middle-aged compared with young adult mice. Donor T cells and neutrophils are more abundant, while B cells are relatively sparse, in central nervous system (CNS) infiltrates of the older mice. Experiments with reciprocal bone marrow chimeras demonstrate that radio-resistant, non-hematopoietic cells play a dominant role in shaping age-dependent features of the neuroinflammatory response, as well as the clinical course, during EAE. Reminiscent of pMS, EAE in middle-aged adoptive transfer recipients is characterized by widespread microglial activation. Microglia from older mice express a distinctive transcriptomic profile, suggestive of enhanced chemokine synthesis and antigen presentation. Collectively, our findings suggest that drugs that suppress microglial activation, and acquisition or expression of aging-associated properties, may be beneficial in the treatment of progressive forms of inflammatory demyelinating disease.
Authors
Jeffrey R. Atkinson, Andrew D. Jerome, Andrew R. Sas, Ashley Munie, Cankun Wang, Anjun Ma, William D. Arnold, Benjamin M. Segal
Abstract
PRDM1 encodes B lymphocyte-induced maturation protein 1 (BLIMP1), also known as a master regulator of T-cell homeostasis. We observed a negative relationship between Blimp-1 and IL-21 based on our previous data that Blimp-1 overexpression in T cells suppresses autoimmune diabetes while Blimp-1 deficient T cells contribute to colitis in NOD mice. Reanalysis of published datasets also reveals an inverse correlation between PRDM1 and IL21 in Crohn’s disease. Here, we illustrate that Blimp-1 represses IL-21 by reducing chromatin accessibility and evicting an IL-21 activator c-Maf from the Il21 promoter. Moreover, IL-21-accelerated autoimmune diabetogenesis in small ubiquitin-like modifier-defective c-Maf transgenic mice can be overridden by Blimp-1 overexpression-mediated reduction in permissive chromatin structures at Il21 promoter. An autoregulatory feedback loop to harness IL-21 expression is unveiled by the evidence that addition of IL-21 induces time-dependent Blimp-1 expression and subsequently enriches its binding to the Il21 promoter to suppress IL-21 overproduction. Furthermore, intervention of this feedback loop by IL-21 blockade, IL-21R.Fc administration or IL-21 receptor deletion, attenuates Blimp-1 deficiency-mediated colitis and reinforces the circuit between Blimp-1 and IL-21 in the regulation of autoimmunity. We highlight the translation of Blimp-1-based epigenetic and transcriptomic profiles applicable to a personalized medicine approach in autoimmune diseases.
Authors
Yu-Wen Liu, Shin-Huei Fu, Ming-Wei Chien, Chao-Yuan Hsu, Ming-Hong Lin, Jia-Ling Dong, Rita Jui-Hsien Lu, Yi-Jing Lee, Pao-Yang Chen, Chih-Hung Wang, Huey-Kang Sytwu
Abstract
Inflammasomes are a class of innate immune signaling platforms that activate in response to an array of cellular damage and pathogens. Inflammasomes promote inflammation under many circumstances to enhance immunity against pathogens and inflammatory responses through their effector cytokines, IL-1β and IL-18. Multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE), are autoimmune conditions influenced by inflammasomes. Despite work investigating inflammasomes during EAE, little remains known concerning the role of inflammasomes in the central nervous system (CNS) during the disease. Here, we used multiple genetically modified mouse models to monitor activated inflammasomes in situ based on oligomerization of apoptosis-associated speck-like protein containing a CARD (ASC) in the spinal cord. Using inflammasome reporter mice, we found heightened inflammasome activation in astrocytes after the disease peak. In contrast, microglia and CNS-infiltrated myeloid cells had few activated inflammasomes in the CNS during EAE. Astrocyte inflammasome activation during EAE was dependent on absent in melanoma 2 (AIM2), but low IL-1β release and no significant signs of cell death were found. Thus, the AIM2 inflammasome activation in astrocytes may have a distinct role from traditional inflammasome-mediated inflammation.
Authors
William E. Barclay, Nupur Aggarwal, M. Elizabeth Deerhake, Makoto Inoue, Toshiaki Nonaka, Kengo Nozaki, Nathan A. Luzum, Edward A. Miao, Mari L. Shinohara
Abstract
Multiple sclerosis (MS) is an autoimmune inflammatory disease of the CNS that is characterized by demyelination and axonal degeneration. Although several established treatments reduce relapse burden, effective treatments to halt chronic progression are scarce. Single-cell transcriptomic studies in MS and its animal models have described astrocytes and their spatial and functional heterogeneity as important cellular determinants of chronic disease. We combined CNS single-cell transcriptome data and small-molecule screens in primary mouse and human astrocytes to identify glial interactions, which could be targeted by repurposing FDA-approved small-molecule modulators for the treatment of acute and late-stage CNS inflammation. Using hierarchical in vitro and in vivo validation studies, we demonstrate that among selected pathways, blockade of ErbB by the tyrosine kinase inhibitor afatinib efficiently mitigates proinflammatory astrocyte polarization and promotes tissue-regenerative functions. We found that i.n. delivery of afatinib during acute and late-stage CNS inflammation ameliorates disease severity by reducing monocyte infiltration and axonal degeneration while increasing oligodendrocyte proliferation. We used unbiased screening approaches of astrocyte interactions to identify ErbB signaling and its modulation by afatinib as a potential therapeutic strategy for acute and chronic stages of autoimmune CNS inflammation.
Authors
Mathias Linnerbauer, Lena Lößlein, Oliver Vandrey, Thanos Tsaktanis, Alexander Beer, Ulrike J. Naumann, Franziska Panier, Tobias Beyer, Lucy Nirschl, Joji B. Kuramatsu, Jürgen Winkler, Francisco J. Quintana, Veit Rothhammer
Abstract
Binding of the bromodomain and extra-terminal domain proteins (BETs) to acetylated histone residues is critical for gene transcription. This study sought to determine the anti-fibrotic efficacy and potential mechanisms of BET inhibition in systemic sclerosis (SSc). Blockade of BETs was done using a pan BET inhibitor JQ1, BRD2 inhibitor BIC1, or BRD4 inhibitors AZD5153 or ARV825. BET inhibition, specifically BRD4 blockade, showed anti-fibrotic effects in an animal model of scleroderma and in patient-derived diffuse cutaneous (dc)SSc fibroblasts. Transcriptome analysis of JQ1-treated dcSSc fibroblasts revealed differentially expressed genes related to extracellular matrix, cell cycle, and calcium signaling. The anti-fibrotic effect of BRD4 inhibition was at least in part mediated by downregulation of Ca2+/calmodulin-dependent protein kinase II α (CaMKII-α) and reduction of intracellular calcium concentrations. These results suggest that targeting calcium pathways or BRD4 might be novel therapeutic approaches for progressive tissue fibrosis.
Authors
Sirapa Vichaikul, Mikel Gurrea-Rubio, M. Asif Amin, Phillip L. Campbell, Qi Wu, Megan N. Mattichak, William D. Brodie, Pamela J. Palisoc, Mustafa Ali, Sei Muraoka, Jeffrey H. Ruth, Ellen N. Model, Dallas M. Rohraff, Jonatan L. Hervoso, Yang Mao-Draayer, David A. Fox, Dinesh Khanna, Amr H. Sawalha, Pei-Suen Tsou
Abstract
BACKGROUND. COVID-19 is a global pandemic caused by the novel coronavirus SARS-CoV-2. Some clinical features of severe COVID-19 represent blood vessel damage induced by activation of host immune responses, initiated by the virus. We hypothesized that autoantibodies against angiotensin converting enzyme-2 (ACE2), the SARS-CoV-2 receptor expressed on vascular endothelium, are generated during COVID-19, and are of mechanistic importance. METHODS. The study was done in an opportunity sample of 118 COVID-19 inpatients. Autoantibodies recognizing ACE2 were detected by ELISA. Binding properties of anti-ACE2 IgM from patients were analyzed via biolayer interferometry. The effects of anti-ACE2 IgM on complement activation and endothelial function were demonstrated in a tissue-engineered pulmonary microvessel model. RESULTS. Anti-ACE2 IgM (but not IgG) were associated with severe COVID-19, found in 18/66 (27.2%) patients with severe disease compared to 2/52 (3.8%) of patients with moderate disease (OR 9.38, 95% CI 2.38-42.0; p=0.0009, Fisher’s exact test). Anti-ACE2 IgM were rare (2/50) in non-COVID-19 ventilated patients with ARDS. Unexpectedly, ACE2-reactive IgM in COVID-19 do not undergo class-switching to IgG, and have apparent KD values of 5.6-21.7nM, indicating that they are T-independent. Anti-ACE2 IgM activated complement and initiated complement-binding and functional changes in endothelial cells in microvessels, suggesting that they contribute to the angiocentric pathology of COVID-19. CONCLUSIONS. Our results identify anti-ACE2 IgM as a mechanism-based biomarker strongly associated with severe clinical outcomes in SARS-CoV-2 infection, which has therapeutic implications. We anticipate that additional IgM responses may identify other COVID-19 subgroups with severe disease, and potentially other serious pandemic illnesses.
Authors
Livia Casciola-Rosen, David R. Thiemann, Felipe Andrade, Maria I. Trejo-Zambrano, Elissa K. Leonard, Jamie B. Spangler, Nicole E. Skinner, Justin Bailey, Srinivasan Yegnasubramanian, Rulin Wang, Ajay M. Vaghasia, Anuj Gupta, Andrea L. Cox, Stuart C. Ray, Raleigh M. Linville, Zhaobin Guo, Peter C. Searson, Carolyn E. Machamer, Stephen Desiderio, Lauren M. Sauer, Oliver Laeyendecker, Brian T. Garibaldi, Li Gao, Mahendra Damarla, Paul M. Hassoun, Jody E. Hooper, Christopher A. Mecoli, Lisa Christopher-Stine, Laura Gutierrez-Alamillo, Qingyuan Yang, David Hines, William A. Clarke, Richard E. Rothman, Andrew Pekosz, Katherine Z.J. Fenstermacher, Zitong Wang, Scott L. Zeger, Antony Rosen
Abstract
Identifying predictive biomarkers at early stages of early inflammatory arthritis is crucial for starting appropriate therapies to avoid poor outcomes. Monocytes and macrophages, largely associated with arthritis, are contributors and sensors of inflammation through epigenetic modifications. In this study, we investigated associations between clinical features and DNA methylation in blood and synovial fluid (SF) monocytes in a prospective cohort of early inflammatory arthritis patients. Undifferentiated arthritis (UA) blood monocyte DNA methylation profiles exhibited significant alterations in comparison with those from healthy donors. We identified additional differences both in blood and SF monocytes after comparing UA patients grouped by their future outcomes, good versus poor. Patient profiles in subsequent visits revealed a reversion towards a healthy level in both groups, those requiring disease-modifying antirheumatic drugs (DMARDs) and those that remitted spontaneously. Changes in disease activity between visits also impacted DNA methylation, partially concomitant in the SF of UA and in blood monocytes of rheumatoid arthritis patients. Epigenetic similarities between arthritis types allow a common prediction of disease activity. Our results constitute a resource of DNA methylation-based biomarkers of poor prognosis, disease activity and treatment efficacy in early untreated UA patients for the personalized clinical management of early inflammatory arthritis patients.
Authors
Carlos de la Calle-Fabregat, Javier Rodríguez-Ubreva, Laura Ciudad, Julio Ramírez, Raquel Celis, Ana B. Azuaga, Andrea Cuervo, Eduard Graell, Carolina Pérez-García, César Díaz-Torné, Georgina Salvador, José A. Gómez-Puerta, Isabel Haro, Raimon Sanmartí, Juan D. Cañete, Esteban Ballestar
Abstract
Cutaneous lupus is commonly present in patients with systemic lupus erythematosus (SLE). T cells have been strongly suspected to contribute to the pathology of cutaneous lupus, yet our understanding of the relevant T cell phenotypes and functions remains incomplete. Here, we present a detailed single-cell RNA sequencing profile of T and NK cell populations present within lesional and non-lesional skin biopsies of patients with cutaneous lupus. T cells across clusters from lesional and non-lesional skin biopsies expressed elevated levels of interferon-simulated genes (ISGs); however, compared to T cells from control skin, T cells from cutaneous lupus lesions did not show elevated expression profiles of activation, cytotoxicity, or exhaustion. Integrated analyses indicated that skin lymphocytes appeared less activated and lacked the expanded cytotoxic populations prominent in lupus nephritis kidney T/NK cells. Comparison of skin T cells from lupus and systemic sclerosis skin biopsies further revealed an elevated ISG signature specific to cells from lupus biopsies. Overall, these data represent the first detailed transcriptomic analysis of the T and NK cells in cutaneous lupus at the single cell level and have enabled a cross-tissue comparison that highlights stark differences in composition and activation of T/NK cells in distinct tissues in lupus.
Authors
Garrett S. Dunlap, Allison C. Billi, Xianying Xing, Feiyang Ma, Mitra P. Maz, Lam C. Tsoi, Rachael Wasikowski, Jeffrey B. Hodgin, Johann E. Gudjonsson, J. Michelle Kahlenberg, Deepak A. Rao
Abstract
We previously found that kidney-infiltrating T cells (KITs) in murine lupus nephritis (LN) resembled dysfunctional T cells that infiltrate tumors. This unexpected finding raised the question of how to reconcile the “exhausted” phenotype of KITs with ongoing tissue destruction in LN. To address this, we performed scRNA-seq and TCR-seq of KITs in murine lupus models. We found that CD8 KITs exist first in a transitional state, before clonally expanding and evolving toward exhaustion. On the other hand, CD4 KITs did not fit into current differentiation paradigms, but included both hypoxic and cytotoxic subsets with a pervasive exhaustion signature. Thus, autoimmune nephritis is unlike acute pathogen immunity; rather the kidney microenvironment suppresses T cells by progressively inducing exhausted states. Our findings suggest that lupus nephritis, a chronic condition, results from slow evolution of damage caused by dysfunctional T cells and their precursors on the way to exhaustion. These findings have implications for both autoimmunity and tumor immunology.
Authors
Shuchi Smita, Maria Chikina, Mark J. Shlomchik, Jeremy S. Tilstra
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